Patent Literature 1 discloses technology that causes an operation performed by one user on a webpage to be reflected on a webpage being viewed by another user. With this technology, operation information related to the operation performed by the one user on a webpage is transmitted to a server. Subsequently, the server processes the webpage on the basis of the operation information, and transmits the processed webpage to each user's terminal (information processing device). Subsequently, each user's information processing device displays the information provided by the server.